As a less-solid version of snow, water is the ideal unstable element in which to improve balance. Concentrate on where your center of balance is as you try this exercise. Start in the shallow end, and progress to deeper water.
Submerge a kickboard to the bottom of the pool and stand on it. Then slowly bring your knees toward your chest, balancing on the kickboard. Keep your back straight and upright and your abs tight throughout the exercise. Balance for five seconds; then push the board back to bottom of the pool. Do 12 reps. as you improve Balancing on the board, roll both ankles to the left, as you would in a ski turn. Balance for five seconds, then roll ankles to the right.